Open issues in Related issues widget no longer visible in Firefox

Summary

The "Related issues" widget no longer shows the list of Open Related issues when using Firefox as a browser. The list appears collapsed, with no possibility to expand it (see screenshot below).

However, Closed Related issues are shown in the widget.

Steps to reproduce

  1. Start Firefox
  2. In Firefox, go to an issue URL that contains related issues: https://gitlab.com/gitlab-org/gitlab-ce/issues/55039
  3. Scroll down to the "Related issues" widget below the issue description

What is the current bug behavior?

The "Related issues" widget shows the count of related issues, but the list of open issues is not visible.

What is the expected correct behavior?

The "Related issues" widget shows the count of related issues, and the list of open issues is visible.

This works in Chrome, but it no longer does in Firefox.

Relevant logs and/or screenshots

Browser's user agent:

Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:64.0) Gecko/20100101 Firefox/64.0

Screenshot: related-issues

The <li> elements which should contain each issue are empty:

<ul class="related-items-list content-list">
    <li data-key="11113319" class="js-related-issues-token-list-item list-item pt-0 pb-0">
        <!---->
    </li>
    <li data-key="15729577" class="js-related-issues-token-list-item list-item pt-0 pb-0">
        <!---->
    </li>
    <li data-key="3625102" class="js-related-issues-token-list-item list-item pt-0 pb-0">
        <!---->
    </li>
    <li data-key="14044437" class="js-related-issues-token-list-item list-item pt-0 pb-0">
        <!---->
    </li>
    <li data-key="1014227" class="js-related-issues-token-list-item list-item pt-0 pb-0">
        <!---->
    </li>
</ul>

Output of checks

This bug happens on GitLab.com

Edited by David Planella